1. Field of Endeavor
The present invention relates to nucleic acid extraction and purification, specifically in regards to automated diagnostic instruments.
2. State of Technology
U.S. Pat. No. 5,234,809 issued to Willem R. Boom et al for a process for isolating nucleic acid provides the following state of technology information: “Known methods of isolating nucleic acid (NA) from complex starting materials like whole blood, blood serum, urine or feces usually comprise lysis of biological material by a detergent in the presence of protein degrading enzymes, followed by several extractions with organic solvents, e.g., phenol and/or chloroform, ethanol precipitation and dialysis of the nucleic acids. These known methods of, e.g., isolating (double-stranded) DNA from clinical material are very laborious and time-consuming. The relatively large number of steps required to purify NA from such starting materials increase the risk of transmission of NA from sample to sample in the simultaneous processing of several clinical samples. When the NA is isolated for the subsequent detection of the presence of NA of, e.g., a pathogen (e.g., a virus or a bacterium) by means of a nucleic acid amplification method for example the utmost sensitive polymerase-chain-reaction (PCR, Saiki et al, Science 230, 1985, 1350), the increased risk of such a transmission of NA between different samples which causes false positive results is a serious drawback.”
United States Published Patent Application No. 2003/0032172 by Billy W. Colston, Jr. et at for an automated nucleic acid assay system provides the following state of technology information: “Nucleic acid amplification and detection is a widely used technique for conducting biological research. Utilization is applied to an increasing range of applications including diagnostics in bench-top research to the clinical arena, genomic screening for drug discovery to toxicology, screening for contamination to identification. Conventional sample preparation and analysis techniques for performing nucleic acid assays are time-consuming, require trained technicians, and lack precise repeatability. New technical developments are needed to improve the performance of nucleic acid amplification and detection . . . . Current instruments for performing chemical synthesis through thermal control and cycling are generally very large (table-top) and inefficient, and often they work by heating and cooling of a large thermal mass (e.g., an aluminum block). In recent years efforts have been directed to miniaturization of these instruments by designing and constructing reaction chambers out of silicon and silicon-based materials (e.g., silicon, nitride, polycrystalline silicon) that have integrated heaters and cooling via convection through the silicon . . . . A problem with standard PCR laboratory techniques is that the PCR reactions may be contaminated or inhibited by the introduction of a single contaminant molecule of extraneous DNA, such as those from previous experiments, or other contaminants, during transfers of reagents from one vessel to another. Also, PCR reaction volumes used in standard laboratory techniques are typically on the order of 50 microliters. A thermal cycle typically consists of four stages: heating a sample to a first temperature, maintaining the sample at the first temperature, cooling the sample to a second lower temperature, and maintaining the temperature at that lower temperature. Typically, each of these four stages of a thermal cycle requires about one minute, and thus to complete forty cycles, for example, is about three hours. Thus, due to the large volume typically used in standard laboratory procedures, the time involved, as well as the contamination possibilities during transfers of reagents from one vessel to another, there is clearly a need for microinstruments capable of carrying out the PCR procedure.”
United States Published Patent Application No. 2007/0148649 by Keiji Shigesada et al for a Cartridge for nucleic acid separation and purification and method for producing the same provides the following state of technology information: “Though nucleic acid has been used in various forms in various fields, it is often the case that only a trace amount of nucleic acid can be obtained, while operations of separation and purification are complicated and time-consuming.”